The Collaborative International Dictionary of English v.0.48:

Tepid \Tep"id\, a. [L. tepidus, fr. tepere to be warm; akin to
   Skr. tap to be warm, tapas heat.]
   Moderately warm; lukewarm; as, a tepid bath; tepid rays;
   tepid vapors. -- Tep"id*ness, n.
   [1913 Webster]

WordNet (r) 3.0 (2006):

tepidness
    n 1: a warmness resembling the temperature of the skin [syn:
         lukewarmness, tepidity, tepidness]
    2: lack of passion, force or animation [syn: tepidness,
       lukewarmness]